The study concerns a type-C virus which has been isolated from two human diploid fibroblast cell strains. It is planned to continue experiments on the in vitro expression of this HEL-12 virus in human cells as a function of time in culture, to demonstrate the role of HEL-12 virus in lesions of systemic lupus erythematosus and to continue work on the coordination of virus release using mouse type C virus, with the cell cycle.